As depicted in FIG. 1, a typical monopolar electrosurgical laparoscopic tool device 100 generally has five main components: a handle 102, an outer shaft 104 extending longitudinally from the handle, an actuation rod 106 extending through the outer shaft, an electrode 108 in electroconductive contact with the actuation rod, and an actuatable end effector 110, disposed at the distal end of the device. The handle 102 illustrated is a “ring handle”, which has a stationary finger portion 112 attached to the outer shaft 104 and an actuatable thumb portion 114 attached to the actuation rod 106. Actuation of the thumb portion 114 by pivoting relative to the finger portion 112 moves the actuation rod 106 axially within the outer shaft 104 to operate the end effector 110. Although many different variations of each of the above components have been introduced into the art, there exists a need for designs that provide efficiency in manufacturing, and that provide surgeons and other users with ergonomic features to enhance safety and ease of use. In particular, there is a need for a handle design that includes an easy-to-use locking feature that provides for secure attachment and convenient detachment of a tool end assembly.